Generally, a capacitor having a large capacitance in excess of 100 μF employs a capacitor block that is fabricated by preparing a plurality of capacitor elements each having a capacitance smaller than 100 μF or of about 100 μF in order to provide a required electrostatic capacitance and connecting the capacitor elements parallel to each other with connectors such as flat-stranded copper wires or the like. Some capacitors have a plurality of such capacitor blocks connected parallel to each other.
When such a capacitor is used as a smoothing capacitor in an electric power converter such as an inverter or the like, a ripple current having a carrier frequency or the like from the inverter flows through the capacitor. At this time, the capacitor elements and the connectors are self-heated and tend to have their service life shortened. Heretofore, parallel flat plates have been used as the connectors by which the capacitor elements are connected parallel to each other for lowering the self-inductance, improving the high-frequency characteristics and reducing the self-heating of the capacitor (see Japanese Patent No. 3771977 and Japanese Patent No. 3357314).